Buckminster-Fullerenes are C60, they are carbon allotropes, which are spherical molecules, also termed buckyballs, composed entirely of carbon. C60 are truncated icosahedrons with a closed-cage structure composed of 20 hexagons and 12 pentagons, and are characterized via mass spectrometry, UV-Visible spectrometry, gas chromatography, and other optical spectroscopy methods. The fullerene C60 has a conjugated electronic structure that allows for a high intermolecular interaction. The molecular packing of the crystalline C60 structures controls its solvation properties. Aromatic solvents such as polar aromatic hydrocarbons, and terpenes, lactones, fatty acid alcohols, or other molecules with similar conjugated structures and high intermolecular interactions will favor solvation.
Carbon nanotubes, namely single-walled carbon nanotubes (SWNTs) are of the fullerene structural family, and are allotropes of carbon with cylindrical nanostructures, note that these can often have fullerene capped ends. The carbon nanotubes have novel properties due to their 1-dimensional (1-D) and sp2 orbital hybridization, which provides them with chemical bonds that are similar to graphite. The strong van der Waals forces of carbon nanotubes allows them to align into roped structures, with diameters close to 1 nm, leading to a one-atom thick structure that is a graphene cylindrical sheet. Of critical importance is their solvation in solvents that have minimal environmental and human exposure liabilities. While some solvation methods are known these are not suitable for large-scale processing. Most of these solvation methods require density-gradient ultracentrifugation of surfactant wrapped nanotubes. Still other methods use chromatographic, gel electrophoresis, or DNA or macromolecular complexation. Nevertheless current applications of single-walled carbon nanotubes are limited due to their lack of solubility, toxicity, environmental liabilities, and efficient and large-scale processing.
Graphene is the basic structural element of carbon allotropes such as fullerenes and carbon nanotubes, and can be considered a type of flat polycyclic aromatic hydrocarbon. The structure of graphene is a one-atom thick planar sheet of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice. Currently the dispersion of graphene is quite difficult, often requiring chemically processed or unique functionalizations that allow for dispersions in some polar aromatics. Still other chemical modifications are possible following treatment with strong acids leading to oxidation, and exfoliation, and an oxidized graphene structure. However this strongly aggressive chemical processing and caustic use of solvents can present time constraint and human and environmental exposure issues. Still other methods employ hydrogenation of graphene, which alters its chemical and electrical properties. While graphene has many exceptional properties, which are often desirable in electrical and thermal applications, its solubility and time-consuming processing, and functionalization can often limit its use.
A limited number of solvents have been used to dissolve fullerenes, graphene, and polymers of fullerenes such as carbon nanotubes. True solutions of fullerenes, graphene, and SWNTs, can be made from either strong aggressive acids, aromatic halogenated hydrocarbons, or toxic aromatic hydrocarbon based solvents that present human and environmental exposure liabilities.
Terpenes are hydrocarbon solvents resulting from the combination of several isoprene units, these can be monoterpenes, sesquiterpenes, diterpenes, and/or triterpenes, with some being linear, while others being cyclical in nature. Within these groups there are other families and grouped subcategories, these differ based on their structural or chemical functional groups, some of the ones used in this formulation include monoterpene cyclic ethers, terpene alcohols, associated fatty acid alcohols, cyclic terpenes, associated lactones, cyclic triterpenoid saponins, and cyclic triterpenoid steroidal saponins. This disclosure also employs lactones, which are internal cyclic monoesters, and fatty acid alcohols, which are aliphatic carboxylic acids.